Mohammed's treatment in an Afghan jail was in breach of previous rulings by British judges, his lawyers told the high court. Photograph: Alamy

An Afghan man detained by British troops who handed him over to an Afghan jail where he says he was brutally tortured is demanding a high court judicial inquiry into the way he was treated.

Lawyers acting for Serdar Mohammed, 24, on Tuesday told the high court that he was held in breach of previous rulings by British judges ordering constant monitoring by the Ministry of Defence of Afghan detainees arrested by UK forces.

They are also asking for an immediate injunction preventing British troops from transferring individuals to the custody of the Afghan security forces. Britain must take all reasonable steps to ensure Mohammed is kept safe from now on and help him overturn his unlawful conviction, his lawyers, Leigh Day, say.

Mohammed was detained by British troops in April 2010 while, he says, he was irrigating his family's fields in northern Helmand province. The British held him for three months before transferring him to the Afghan National Directorate of Security (NDS) who kept him at Lashkar Gah before transferring him to other NDS facilities.

He says he was beaten by NDS guards with sticks and electric cables, hooded, suspended by one hand and shackled in excruciating positions for prolonged periods. On one occasion, his torturers wrenched and twisted his testicles so hard that blood came out of his penis, he says. He eventually signed a "confession" admitting to being a member of the Taliban and was sentenced to 16 years in prison after a trial lasting 15 minutes conducted in a language, his lawyers say, he did not understand.

His claims echo those of other detainees transferred to the NDS interviewed for a UN report on detainee treatment released in October last year. The report found that 46% of all detainees interviewed had been tortured in Afghan custody and that torture in five NDS facilities, including those of Herat, Kandahar, Khost and Kabul, was systematic.

Richard Stein, head of Leigh Day's human rights department, said: "There remains a huge gap in Afghanistan between what are agreed international standards of conduct when dealing with detainees and what is in fact happening on the ground." Keren Adams, a partner in the law firm who visited Mohammed in prison in Afghanistan, said: "Immediate steps must now be taken by the secretary of state [for defence] to ensure that Mr Mohammed suffers no further abuse and is able to challenge his convention in court with the benefit of full legal representation."

The high court last year imposed strict conditions on the transfer by British forces of suspected insurgents to Afghan detention centres. Transferring suspects to NDS facilities in Kandahar and Lashkar Gah, Helmand's provincial capital, should be allowed provided that existing safeguards were "strengthened by observance of specified conditions", they said. The court insisted safeguards had to include the right of British monitors to get access to the detainees regularly.

The Ministry of Defence said British troops had acted after receiving information that Mohammed was a Taliban commander. It said it was not aware he had made any allegations of ill-treatment when he was in British custody, the military police were still investigating the case and the UK ambassador in Kabul had taken it up with the head of the NDS.